There has conventionally been developed a technology that an exhaust gas purification device (diesel particulate filter) is provided in the exhaust path of an engine, and the exhaust gas discharged from a diesel engine is purified and treated by means of the oxidation catalyst of the exhaust gas purification device or a soot filter (for example, see Patent Literature 1). Also, in recent years, in the fields of work machines such as a construction machine or an agricultural machine, it has been demanded that the exhaust gas purification device is provided in the diesel engine used in the aforementioned machines, in view of environmental countermeasures (for example, see Patent Literature 2).